Appliance for extinguishing fires and suppressing explosions



Oct. 16, 1956 A. MATHISEN 2,766,832

APPLIANCE FOR EXTINGUISHING FIRES AND -SUPPRESSING EXPLOSIONS Filed Jan.18, 1954 2 Sheets-Sheet l INVENTOR MIKE/v5 M677 /SEA ATTORNEYS Oct. 16,1956 A. MATHISEN 2,766,832

APPLIANCE FOR EXTINGUISHING FIRES AND SUPPRESSING EXPLOSIONS Filed Jan.18, 1954 2 Sheets-Sheet 2 L 5/ 49/1 r f r/\\ Ill wvavro 15 F5 MA 755Mark/Maw, Mwm

A 7' TOPNEYS' Patented Oct. 16, 1956 United States Patent OfiiceAPPLIANCE FOR EXTIN GUISHIN G FIRES AND SUPPRESSING EXPLOSIONS AndersMathisen, London, England, assignor of one-half to GravinerManufacturing Company Limited, London, England, a British company, andone-half'to The Wilkinson Sword Company Limited, London, England, aBritish company Application January 18, 1954, Serial No. 404,574

Claims priority, application Great Britain January '26, 195B:

11 Claims. (Cl. 169--9) This invention relates to appliances of the kindadapted to contain suppressant which can be rapidly discharged forextinguishing fires or suppressing explosions.

, According to the present invention there is provided an appliance ofthe kind specified, comprising a closure member of ductile materialsealing a discharge outlet of the appliance, and an explosive chargemounted adjacent said closure member and adapted, upon ignition, toburst said closure member without any substantial fragmentation thereofto give full bore discharge through said outlet.

The invention also provides an appliance of the kind specified,comprising a suppressant container, adapted to contain liquidsuppressant subjected to a predetermined pressure, said container havingone or more discharge outlets,'a closure member sealing each dischargeoutlet, an explosive charge positioned in close proximity to saidclosure member, liquid suppressant lying between the explosive chargeand the closure member whereby upon ignition of said charge theresultant explosive force is transmitted through the liquid to actsubstantially uniformly upon, said closure member, the material of theclosure member being such that the force of the explosion tears saidclosure member without any substantial fragmentation thereof and forcesthe torn portions against'the walls of the outlet to give substantiallyunrestricted passage for the suppressant. a .The invention furtherprovides an appliance of the kind specified comprising a suppressantcontainer of bottle or spherical shape adapted to contain suppressantunder apredetermined pressure, at least' one discharge outlet from saidcontainer, a closure member of ductile material adapted to seal saidoutlet, said closure member being relatively thin and having the shapeof a cap of a sphere, the concave surface of said cap being in contactwith the suppressant contained in the appliance, and an explosive chargemounted opposite the concave surface within the container of, say, 250lbs. per square inch at room temperature. The discharge head comprises atubular member 11 which is welded to the mouth of the bottle 10 at 10aand is provided witha large aperture at 1111 so that the interiors ofthe container 10 and the tubular member 11 are in communication.Opposite the aperture 11a a further small aperture 11b is formed throughwhich the bottle may be filled, this aperture being closed by afiller-plug 12 which screws into a threaded boss 13 welded on theoutside of the tubular member 11. A sealing washer 14 is forced by thehead of the plug 12 into engagement with a knife-edge13a formed on theboss 13. Subsequently a cap 15 is screwed on to the boss 13 to cover thefiller-plug 12. A pipe connector 16 is screwed into one end of thetubular member 11 and is locked to the mouth of the tubular member 11 bya tab washer 17.

The other end of the tubular member is internally threaded to engage thethreaded outer periphery of a flange 18a forming part of a shroud 18 inwhich a removable explosive cartridge is housed. The body 19 of thecartridge is externally shaped at 19a to receive a retaining nut 20which engages the shroud 18 and secures the cartridge in position, acirclip 21 secured in a groove in the outer periphery of the cartridgebody 19 preventing inadvertent untbreading of the retaining nut 20. Theend of the retaining nut 20 is staked into slots formed bycastell-ations 18b on the end of the shroud 18. The opposite end of theshroud 18 is closed by a metal thimble 22 the function of which will bedescribed below.

The body 19 of the cartridge houses a moulded fuse body 23 of insulatingmaterial which carries two plug pins 24 only one of which can be seen inthe drawings. One end of the fuse body 23 carries a bobbin 25 upon whichis wound two fuse Wires 26 whose ends are connected in parallel to theplug pins 24. The bobbin 25 is surrounded by a gunpowder charge 27 whichis contained within a and adapted, when ignited, to burst open theclosure member into petal-like portions which are forced against thewalls of the outlet to give full bore discharge therethrough.

Two embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

Figure 1 is a side elevation of one construction of appliance inaccordance with the present invention, while Figure 2 is a sectionalside elevation of the head only of the appliance shown in Figure 1;

Figure 3 is a similar view of the head only of a second construction inaccordance with the invention, this construction having three separatedischarge outlets, while Figure 4 is an upward plan view in thedirection of the arrow III in Figure 3.

Referring now to Figures 1 and 2, these show a bottlelike metalcontainer 10 to the mouth of which a discharge head is secured, thecontainer 10 being adapted to contain a suppressant, for example methylbromide, which is under nitrogen pressure givinga total pressure tubularmetal housing 28 to which a copper end cap 29 is soldered. To insulatethe powder 27 from the metal housing 28, the former is enclosed in asilicone rubber bag 30 having an O-ring end flange 30a which is spreadout when, during production the end of the cartridge body 19 is spunover the housing 28 to retain it in position. External sealing of thecartridge is effected by an O-ring seal 31 trapped between a flange 19bon the cartridge body and a corresponding shoulder 18b on the innersurface of the shroud 18. The interior of the cartridge body 19 isthreaded at 190 to receive an externally threaded electrical socket (notshown) by which the plug pins 24 are connected to an igniting circuit.

The outlet orifice is sealed by a closure cap 32 which has the shape ofa cap of a sphere, and is provided with a skirt portion 32a which bearsagainst the inner surface of the tubular member 11, a good fillet ofsolder being applied between the end of the skirt portion 32a and theadjacent surface of the tubular member 11. The cap 32 rests against ashoulder 110 formed in the member 11, which shoulder assists inresisting any movement of the closure cap 32 under the internal pressureto which the suppressant is subjected. The cap 32 has five uniformlyspaced radial grooves 32b formed on its convex surface, these groovesbeing of truncated V-section.

The main object of providing the thimble 22 is to ensure that afterelectrical ignition the charge is almost completely burnt before theexplosive force can act on the cap 32. Thus the thimble is designed sothat it will not burst until the explosive force has been built up bythe almost complete burning of the charge, and

- thereupon shattering of the thimble releases a pent-up explosive forcewhich acts through the liquid interposed between the thimbl 22 and cap32 upon substantially the whole of the unsupported surface of the cap32. This ensures satisfactory tearing,'without fragmentation,

along the grooves 32b to form five petal-like portions which are forcedback against the inner wall of thepipe connector 16 to give asubstantially unrestricted bore for discharge of the suppressant.

While not restricted to any particular number of grooves, it hasbeenfound that five grooves give particularly satisfactory bursting ofthe cap 32.

Byway of example only, it may be stated that.satisfactory operation hasbeen obtained using a drawn copper cap of 18 S. W. G. and 1 /2 inchesouter'diameter, the grooves being machined therein to a depth of'0.0l8to 0.020 of an inch, and a copper thimble of 24 S. W. G. (0.022 of aninch) thickness. With such a cap and thimble it was found that thedistance between them was not critical, and satisfactory results wereobtained with distances varying'betwcen 0.150and 0.375 of an inch.Bursting of the cap 32 occurred within 30 milliseconds of theapplication of the ignition current, and it was found possible todischarge the suppressant in a period of as little as 400 millisecondswith six pounds of suppressant or 600 milliseconds with twelve pounds ofsuppressant at 250 p. s. i. through a bore of'l inches. Clearly the useof greater bores is readily possible.

Such appliances are, therefore, of great value in cases wheresuppressant must be distributed at a very rapid rate, for example, foruse in aircraft, power plants or in connection with the suppression oralleviation of explosions, the extinguisher in this latter case beingoperated by means for detecting the explosion while it is still in anincipient stage.

While it is the usual practice in the case of aircraft to connect suchautomatically operated extinguishers to spray pipe systems,extinguishers according to the present invention are particularlyadapted for use in so-called high-rate discharge systems, in which nopipe or only a short pipe is used in order to enable higher dischargerates to be obtained. A spray nozzle may be used to terminate thedischarge outlet, or any short pipe con nected thereto.

it will be understood that the method of securing the cartridge enablesreplacement of the cartridge at specified periods. Moreover, afterfiring the shroud can readily be withdrawn :and replaced, and the burstcap can be machined out anda new cap fitted. After refilling, the bottleis once more ready. for use.

Referring now to Figures 3 and 4, these show an appliance having adischarge head with three discharge outlet connections 40, 41 and 42mountedon a T-piece 39. The construction of this discharge head issimilar to that shown in Figure 2, but because of the extra outlets theapertures for the cartridges 43,44 and 45 are formed in the bottom ofthe head. The three thimbles, only two of which 46 and 48are shown, aremounted in the side at one end of the cartridges 43 to 45 so that uponignition the force of the explosive charge is directed towards theassociated cap, only 49 and 51 of which are shown. In this connection itmay be mentioned that where selective bursting of the caps is required,it has been found that it is quite possible to fire one or two explosivecharges and burst the associated cap Without bursting the other caps orcap.

With this particular construction of head it is necessary to insert thecaps 49 and 51 through their associated discharge outlets and it is notpossible, therefore, to form supporting shoulders in the interior of theT- piece 39. For this reason annular nuts, only 52 and 54 of which areshown, are provided for supporting the periphery of each cap. Thefilling opening is made in that side of the T-piece 39 which does notinclud a discharge outlet, the filler plug 55 being covered by a cover56 as before.

While in the arrangement shown three separate electrical sockets arerequired, the arrangement can be readily modified to combine the plugpins and cartridges so that only a single multiple socket is required.

It should be mentioned that the effect obtained by the thizrnble may beachieved by other constructions; thus, for example, instead of having athimble soldered to the body of the shroud, the shroud may be machinedto provide a weakened wall portion of suitable extent which isburst bythe explosive force in the same manner as described for the thimble.

Although the closure members have been described as being made of copperthey may be made of other metals or alloys which will tear in therequired manner when subjected to the force of the explosive charge;silver or alloys thereof are suitable materials for the purpose.

It will also be appreciated that while reference has'been made to theuse of a gunpowder charge, other forms of explosive charge, for exampledetonators, may be used.

What I claim is:

1. In a container adapted to contain liquid under a predeterminedpressure and having at least one discharge outlet, a metal closuremember sealed across the discharge outlet, an explosive chargepositioned in close proximity to said closure member but out of contacttherewith, said explosive charge having an igniting wire therein, liquidsuppressant lying between the explosive charge and the closure memberwhereby upon electrical ignition of said charge the resultant explosiveforce is transmitted through the liquid to act substantially uni formlyupon said closure member, said closure member being'of ductile metal sothat the force of the explosion tears said closure member without anysubstantial fragmentation thereof and forces the torn portions againstthe sides of said outlet to give substantially unrestricted passage fordischarge of the liquid.

2. In a liquid container provided with at least one discharge outlet forthe liquid, a closure member of ductile metal extending substantiallyacross said discharge outlet, an explosive charge, and an electricaligni: tion wire for igniting said charge, said charge being immersed inthe liquid and mounted a short distance from said closure member wherebyupon electrical ignition of said charge the resultant explosion istransmitted through the liquid to burst said closure member without anysubstantial fragmentation thereof and forces the torn, portionsof theclosure member'against the walls of the discharge outlet to givesubstantially unrestricted passage for the liquid to pass through saidoutlet.

3. In a fluid container adapted to contain liquid under a predeterminedpressure and provided with at least one discharge outlet, a closuremember of ductile metal sealed across said outlet, said closure memberbeing relatively thin and having the shape of a cap of a sphere, theconcave surface of said cap being in contact with the liquid containedin said container, and an explosive charge having electrical ignitingmeans, said explosive charge.

being supported in the liquid at a short distance from said concavesurface whereby therexplosive force resulting from ignition of saidcharge is transmitted through the liquid to burst the closure memberinto petal-like. portions which are forced against the walls of saidoutlet to allow full-bore discharge therethrough.

4. In a container having at least one. discharge outlet, liquid firesuppressant, a ductile metal closure member sealing said outlet, saidclosurememberhaving the shape of a cap of a sphere and being formed withpredeterconcave surface in contact with the liquid contents, the convexsurface of said closure member being radially grooved, and an explosivecharge having electrical igniting means, said charge being positionedwithin the liquid and spaced apart from said concave surface whereby theexplosive force resulting from ignition of said charge is transmittedthrough said liquid and causes tearing of said copper closure memberalong the radial grooves to open said closure member into petal-likeportions without fragmentation.

6. A fluid container according to claim 5, in which five grooves areformed on said convex surface.

7. In a fluid container provided with at least one discharge outlet, aclosure member sealed across said discharge outlet, 21 housingpositioned adjacent said closure member, part of said housing beingfrangible when subjected to a predetermined gas pressure, and anexplosive charge enclosed in said housing, said explosive charge beingprovided with an igniting wire, said charge being spaced from thefrangible part of said housing to leave a substantial gas space wherebya pressure is built up in said gas space during initial burning of saidcharge and said frangible part of the housing is shattered when the gaspressure reaches said predetermined pressure to release the pent-upforce of the explosion to act upon said closure member.

8. In a fluid container provided with at least one discharge outlet, aductile metal closure member sealed to the sides of said outlet, anexplosion resistant housing having an opening in the walls thereofadjacent said closure member, a frangible member sealed across saidopening, said frangible member being adapted to burst under apredetermined pressure, and an explosive charge having an electricaligniting wire, said charge being positioned within said housing andspaced from said frangible member to leave a gas space between saidcharge and said frangible member, whereby upon ignition of saidexplosive charge pressure is built up in said gas space until saidpredetermined pressure is attained.

9. In a fluid container adapted to contain liquid under a predeterminedpressure and provided with at least one discharge outlet, a thin copperclosure member sealed across said outlet, said closure member having theshape of a cap of a sphere and being mounted with its concave surface incontact with the liquid contents, the convex surface of said closuremember being radially grooved, an explosion resistant housing positionedwithin the liquid and having an opening in the walls thereof facing saidclosure member, a frangible member sealed across said opening and spacedapart from said closure member, said frangible member being adapted toburst under a predetermined pressure, an explosive charge, and anelectrical ignition wire for igniting said charge, said charge beingenclosed within the sealed housing and spaced from said frangible memberto leave a substantial gas space between said charge and said frangiblemember, whereby upon ignition of said explosive charge pressure is builtup in said gas space until said predetermined pressure is attainedwhereupon said frangible member is shattered and the released explosivepressure is transmitted through the liquid to burst said copper closuremember.

10. In a container for liquid, said container having a dischargeorifice, an unshatterable ductile metal closure ember for said orifice,an explosive charge, electrical igniting means for said charge, anopen-ended housing in which said explosive charge is mounted, afrangible thimble closing the open end of said housing, said thimblelying within the liquid in the container and being positioned a shortdistance from said ductile metal closure member, ignition of saidexplosive charge resulting in a build-up of pressure in the interior ofthe thimble until said thimble shatters to release the pent-up force ofthe explosion which is transmitted through the liquid surrounding thethimble to burst said closure member.

11. In a liquid container having at least one discharge outlet, ametallic closure member sealing said discharge outlet, a closed housingextending through the liquid, a portion of said housing lying close tosaid closure member with liquid interposed between said portion of thehousing and said closure member, said portion of the housing beingadapted to burst at a predetermined pressure, an explosive chargemounted in said housing and spaced from said portion of the housing toleave a substantial gas space in which pressure is built up duringburning of said explosive charge, said portion of the housing burstingwhen the gas pressure resulting from ignition of the explosive chargereaches said predetermined pressure, whereby the explosive force isreleased and is transmitted through the liquid to unseal the dischargeoutlet.

References Cited in the file of this patent UNITED STATES PATENTS1,708,869 Buddecke Apr. 9, 1929 2,057,840 Neumann Oct. 20, 19362,417,082 Mapes et a1 Mar. 11, 1947 2,436,364 McDowell Feb. 17, 19482,713,391 Buckhaltz July 19, 1955

